Honing method and apparatus



Nov. 21, 1950 M. c. HUTTO HONING METHOD AND APPARATUS 5 Sheets-Sheet 1 Filed Nov. 29, 1947 7 1 7 jZ i orne g/a.

. INVENTOR.

' fir ed Q0 3117 Nov. 21, 1950 M. c. HUTTO 2,530,615

HONING METHOD AND APPARATUS Filed Nov. 29, 1947 5 Sheets-Sheet 5 J6 8f 7 56 win 3 3 7 5 i2 i3 .78

Nov. 21, 1950 M. c. HUTTO 2,530,615

.HONING METHOD AND APPARATUS Filed Nov. 29, 1947 Sheets-Sheet 4 Nov. 21, 1950 M. c. HUTTO I 2,530,615

HONING METHOD AND APPARATUS Filed Nov. 29, 1947 5 Sheets-Sheet 5 I Fig .6. 770

l 'atented Nov. 21, 1956 UNITED STATES PATENT OFFICE 2,530,615 HoN-ING METHOD AND APPARATUS Marsden C. Hutto, Detroit, Mich. Application November 29, 1947, Serial No. 788,834

29 Claims.

This invention relates to a honing method and apparatus and more particularly to the honing of radially expansible circular articles such as piston rings.

Particularly with piston rings, it is desirable that they be accurately finished so as to engage continuously and accurately the wall of the sur rounding cylinder while pressed against the cylinder Wall by the resilience of the piston ring. Such finishing operations may be performed by moving the rings relative to honing surfaces engaging the peripheries of the rings. In order to impart such relative movement it has been the practice to so clamp the rings to the propelling mechanism that the rings are incapable of expanding during the honing thereof. The result is that the ring surfaces are not accurately finished to the exact shape or contour that they must have in order to fit tightly and continuously the walls of a cylinder when they are free to expand under their inherent resilience.-

It is also desirable that the piston rings be honed to have a frusto conical taper in order to provide maximum sealing effect between the piston and the surrounding cylinder and in order to have minimum contact with the cylinder wall.

It is also desirable that the-honing of the piston ring proceed as rapidly as possible tothe end that the piston rings can be individually honed thereby to avoid the necessity of assembling the piston rings in gangs preparatory to honing.

It is also desirable that with such individual honing of the piston rings the rings be capable of being rapidly inserted in the'honing apparatus and rapidly removed therefrom so as to reduce the total time of the honing operation to a minimum.

It is accordingly one of the principal objects of the present invention to provide a honing" method and apparatus in which the piston rings are rapidly honed to a contour which will con tinuously and accurately engage the wall of the cylinder in which the piston rings are fitted. Such contour is provided by supporting the rings during honing so that they are free to expand into engagement with a honing device which embraces the peripheral surface of the rings, whereby such peripheral surfaces are honed under substantially the same conditions of confinement and resilient expansible stress as obtained' when the rings are subsequently used in a cylinder. Such rapidity of the honing is obtained by impressing fluid pressure internally against 2. pressure of the rings against the honing devices and thereby accelerate the honing action.

Another object of the invention is to provide such a method and apparatus in which the degree of internal fluid pressure so impressed upon the rings can be adjusted to suit the particular ring being honed.

Another object is to provide such a method and apparatus which bones the ring to providean external frusto-conlcal taper thereby to provide a ring having the maximum sealing effect.

Another object is to provide such a method and apparatus in which the piston rings are honed individually thereby to avoid the time and labor spent in assembling the rings in gangs upon a suitable fixture and also to avoid the errors of misalinementand fit incident to such assembly.

Another object is to provide such a method and apparatus in which the rings are rapidly inserted into and removed from the honing apparatus so as to reduce the total time required for honing to a minimum.

Another object is to provide such a method and apparatus which will hone piston rings, some of which may have non-parallel end faces, so as to be of wedge form.

Another object is to provide an improved resilient reactance device in the form of an air cushion against which the piston ring being honed is worked.

Another objectis to provide a piston ring honingapparatus which can be made as automatic as desired.

Another object is to provide such apparatus having braking means to bring the piston ring supporting parts rapidly to a standstill after each honing operation.

Another object is to provide suchhigh speed honing apparatus which is of simple constructionand which will stand up under conditions of severe and constant use without getting out of order or requiring repairs.

Other objects and advantages of the invention will appear from the following description and drawings in which:

Fig. 1 is a fragmentary vertical longitudinal section, partly in elevation, of honing apparatus embodying the present invention.

Fig. 2 is a fragmentary horizontal section taken on line 22, Fig. 1.

Fig. 3 is an enlarged fragmentary sectional view similar to Fig. 1 and showing the position of the parts with the piston ring about to enter the honing zone.

the piston rings soas to augment the expansive Fig. 4 is a further enlarged fragmentary sec- 3 tional view similar to Figs. 1 and 3 and showing the position of the parts with the piston ring being acted upon by the honing stones.

Fig. 5 is a fragmentary sectional view similar to Fig. 3 and showing the position of the parts with the honed piston ring leaving the honing stones preparatory to removal from the apparatus.

Fig. 6 is a fragmentary sectional view similar to Figs. 3 and 5 and showing the manner in which the parts of the honing apparatus separate to permit ready removal of the honed piston ring and the replacement of an unhoned piston ring.

Figs. '7 and 8 are horizontal sections taken on the correspondingly numbered lines on Fig. 5.

Fig. 9 is an enlarged, fragmentary, vertical section taken on the line 99, Fig. '7.

Fig. 10 is a fragmentary sectional view similar to Fig. 3 and showing the position of the parts when the apparatus is in honing operation as shown in Fig. 4.

Fig. 11 is a fragmentary sectional view similar to Fig. 10 and showing the position of the parts when the piston ring is removed from the grinding zone as shown in Fig. 6.

'Fig. 12 is a cross-section through a tapered piston ring ground in accordance with this in vention.

The honing apparatus is shown as supported by a base which is shown as comprising a pair of I spaced sheet metal standards l5 supporting a sheet metal top It, the edges of which are flanged upwardly to retain any kerosene dropping thereon. This top supports a heavy metal plate It which forms the bed or base plate of the apparatus.

The piston ring is reciprocated and rotated in contact with the honing stones and to effect such rotation an electric motor 2! is mounted on the base 22 of a pedestal 23 carried by the bed or base plate it, this pedestal being formed to provide a horizontal hollow arm 24. In this arm is suitably journaled, as best shown in Fig. 2, a longitudinal horizontal shaft 25, a pulley 25 being fast to the rear end of this shaft and connected by a drive belt 28 with a pulley 29 fast to the shaft of the electric motor 2!. A worm 30 is fast to the forward end of the shaft 25, this worm being housed within the outer or forward end of the arm 24 and meshing with a worm gear 3! which is journaled in the outer or forward end of the arm 24 to rotate about a vertical axis. For this purpose the lower end of the hub of this worm gear 3i is shown as journaled in a lower bearing 32 and on a supporting thrust bearing 33 carried by the lower wall of the hollow arm 24 and the upper end of the hub is shown as journaled in in an upper bearing 34 carried by a supporting ring 35 mounted on the top wall of the hollow arm 24.

The worm wheel 3| is splined to a vertical shaft 35 so that this shaft is capable of vertical reciprocation in the hub of the worm gear 3! but is compelled to rotate therewith. To reciprocate this vertical shaft 35, a tubular post 33 is mounted on the supporting ring 35, this tubular post in turn supporting a hydraulic cylinder 35 in coaxial alinement above the shaft 35. A piston is arranged in this hydraulic cylinder 39, the piston rod 4| of which extends downwardly through a gland or stuifing box 42 in the lower end of the hydraulic cylinder and which also extends upwardly through a gland or stuffing box 43 in the upper end of the hydraulic cylinder. Oil or other liquid is introduced into and exhausted from the upper end of the hydraulic cylinder 39 through a line 44 and is introduced into and exhausted from the lower end of the hydraulic cylinder through a line 45. The lower end of the piston rod 4! extends through a ring 45 and has a collar 47 fastened to its lower end, a pair or radial and thrust bearings 48 and 49 being interposed one between the collar 4'! and ring 45, and the other between the ring 46 and a bearing housing between the sections of which the ring 46 is clamped. This bearing housing and its bearings provides a connection between the piston rod 4! and splined shaft 35 through which the shaft 35 is compelled to reciprocate vertically with the piston rod 4| but is free to rotate independently of this piston rod.

The lower end of the splined shaft 36 is formed to provide an annular outwardly extending flange or head 52 and a stub extension 53 projecting coaxially downwardly below this flange. This downward extension is internally formed to provide a hexagonal or out-of-round socket 54 and is externally provided with a bead 55 at its lower end. The flange 52 is also recessed on its underside to receive a rubber ring 56 which is preferably made of synthetic rubber such as neoprene to resist the effect of kerosene. A metal piston ring holding collar or plate 58 is held against the underside of the rubber ring 55 by an annular series of screws 59 extending upwardly into the flange 52 and the bore of this ring is fitted around the bead 55 at the lower end of the downward extension 53 of the splined shaft 36. The underside of this collar or plate is flat and disposed perpendicular to the axis of the shaft 35 so as to engage the upper face of the piston ring 20 during the honing peration. This collar or plate 58 is also provided below the downward extension 53 of the shaft 35, with a'plurality of radial ducts 60 which extend therethrough for a purpose which will presently appear.

The bed or base plate i 8 is apertured to receive a stationary vertical cylinder 55, this cylinder being arranged coaxial with the shaft 36 and having an outwardly projecting flange which rests on the bed or base plate 15 and is secured thereto in any suitable manner as by the screws 68. An end head 59 is secured to the lower end of this cylinder 55 in any suitable manner, this end head being formed to provide a central tubular part '19 which forms a cylindrical bearing and slideway 7! for the lower end of a tubular shaft 72. The lower end '13 of this shaft is of reduced external diameter while the upper end 14 is of larger external diameter to provide a downwardly facin annular shoulder or step 15 near the center of the shaft. The extreme upper end of this shaft 12 is formed to provide an annular outwardly extending flange l6 and a stub extension ll projecting coaxially upwardly above this flange and toward the downward stub extension 53 of the shaft 35. The flange 15 supports a metal collar or plate 78 which is fitted around the stub extension 71. The upper side of this collar or plate 18 is flat and disposed perpendicular to the axis of the shaft 12 so as to engage the under face of the piston ring 20 during the honing operation. This collar or plate is also provided, above the upward extension 17 of the shaft 12 with a plurality of radial ducts 19 which extend therethrough for a purpose which will presently appear.

The upper end of the bore 80 of the shaft 12 is threaded to receive the threaded base of a hexagonal or out-of-round neck 8| which projects grease through a radial grease duct I02 in the partition coaxially "upwardly from the shaft '12 to interfit with the hexagonal or out-of-round socket 54 provided in theilower end of the shaft 36. This hexagonal neck '8I is provided with a vertical bore 82 extending part way'up from the bottom of .its base and a'plurality of radial ducts 88extend fromthe upper end 'of this bore 82 to the exterior .of the hexagonal neck. Kerosene is forced through these radial ducts 83 into the chamber provided bythe metal collars or plates 58, "l8,-piston ring 29 and shafts 35, I2 and for this purpose-akerosene pressure line '84 is connected-with'the lower *endof the tubular part IU of the cylinder end head =59, this-kerosene pressure line 84 being in communication with these ducts 83 through the bores "H, 88 and 82 ofthe tubular part 18, shaft 72 and hexagonal neck 8i, respectively.

The shaft 12 is non-rotatably but axially slidably fitted in a sleeve 85, the flange T6 at the upper end of the shaftIZ resting on the upper end of this sleeve. Toprovide such non-rotatable but axial slidable connection between the shaft IZ'and sleeve'85, a pin 87 is secured in the sleeve 85 to project into a longitudinal groove in the shaft I2 as best shown in Fig. 3. The upper end 86 of the bore of this sleeve 35 is of enlarged diameter to fit-the larger external diameter of the upper end of the shaft 72 while the lower end 88 of the bore of this sleeve 85 is of reduced diameter to fit the lower end I9 of reduced diameter of the shaft 12, an upwardly facing annular shoulder or step 89 being thereby provided in the bore of this sleeve 85 in opposing relation to the downwardly facing annular shoulder or step of the shaft 12. An annular chamber '90 is thereby provided by the shaft I2 and sleeve 85 between these annular shoulders or steps 15, 89.

This chambered part of the shaft 72 and sleeve 85is embraced by a stationary sleeve 9| which forms a bearing and slideway for the movable sleeve-85 and is supported by a horizontal partition 92 extending horizontally across the center of the stationary cylinder 55 and dividing it into an upper chamber 93 and a lower chamber 94.

Air under pressure is supplied to the lower chamber 94 through an air pressure line 95 connected withthe lower end head 69 of the sta tionary cylinder 65. This air is supplied through the bottomwall of this chamber 94 so as to bubble up through the oil therein and pick up lubricant for subsequent deposit on the moving parts which this air passes. This air under pressure escapes through a port 96 when this port 98 is brought into register with an annular groove 98 This air under pressure passes sleeve 85 in line with the annular groove 98 and chamber 98. This air under pressure escapes from the annular chamber 98 into the vented chamber 93 when this annular chamber 98 is :brought into communication with a port Ibt through the wall of the movable sleeve 85 above its annular groove 98. surfaces of the stationary sleeve 9I, movable The frictionally engaging sleeve 85 andshaft '82 can be lubricated through introduced from a grease fitting IQI '92 into the annular groove 98 of the movable sleeve "85 and thence through the duct 99 into the annular chamber 90.

The upper end of the movable sleeve 85 is formed to' provide an outwardlyextending brake flange 1-03, the upper surface of which is adapted to engage theunder'surface of a brake ring IM, the rim ofwhich is secured over the otherwise open upper end of thestationary cylinder 65'by screws I05 or in any othersuitablemanner. The brake flange I93 of the movable-sleeve is vertically apertured, as indicated at I89, to permit kerosene to fiow from the honing zone above,.this kerosenetherebyescaping into theupper chamber 93 of the stationary cylinder 65 and from whioh it escapes through a 'kerosenedrain pipe I98. A cylindrical sheet metalrguard H59 is secured to the underside of the brake flange I03 over the stationary sleeve 9I to protect the joint between the stationary sleeve 9| and'itsmovable sleeve 85 f10mthe kerosene.

An annular base :I. I8 .for the honing stones is secured, as'byscrews III, tothe rim'fifi of'the fixed cylinder, thisibase being in the form of a disk H2 having a bore fitting the periphery of the brake ring IE8 and havingan annular-flange or rim I I'Brising fromitsperiphery. ;In:this -annular base is secured, as byscrews H4, a ring I I5, the upper side of zthis ring being radially grooved to provide a plurality of parallel sided slideways :llfi in each of which a stone holder H3 is slidingly fitted. Each stone holderis in the form of a metal block slidingly fittedin its radial guideway and the several stone holders are retained in these guideways ,5 by an annular cover plate I Ii9fitted'on top of theradially grooved ring M5 within the rim N3 of the annular base H9 and securedby screws I2I extending into the grooved ring H5. This cover plate is provided with an annular flange I 29 --around itsbore E22 and on this flange is secured, as by screws I23, the rim I2 5 of a piston -rin-g;receiver I25. The upper part I26 of'the bore in this piston ring receiver I25 is of frusto-conical tapering form, theenlarged upper end of which islof greater diameter than the free piston ring 28 whilethe lowerend thereof is of smaller diameter than the freepistonring 28 sothat a piston ring placed in this tapered bore and-moved downwardly is contracted and placed under stress. From the lowerend of the tapering upper part I25 of the boreof the piston ring receiver, the piston rings 28 enter a cylindrical 1oWerpart-I-28 of this bore, this cylindrical lower part 'I28 of this bore being of the minimum diameter-of the tapering frusto-conical upper partof-the bore sothat the piston rings 29 passingtherethrogugh are held in a contracted or stressed condition.

Oil-moving downwardly "fromthe lower part I28 of .the bore of .thepiston ring receiver I25, the piston rings encounter honing stones I38 made of abrasive particles bonded together and each secured'to the forward end of the corresponding :stone holder H8 in any suitable manner. The inner or working face I3I of each stone I30 conforms at its, upper edge to the cylindrical lower part I23 ofithe bore in the piston ring receiver 125, these working faces being thereby in the form of segments of a circle. However, an important feature of the invention resides in the fact that the working faces I3I of the several honing stones are not cylindrical but are of tapering frusto-conical'form as best shown in Fig.4. 'Thus, the segmental working face I3I of each honing stone extends downwardly and inwardly to a smaller radius. In consequence, as the piston ringZll is reciprocated vertically in contact with the working faces I3I of these stones,.-.a 'frusto-conical taper I32 is provided on. the :pe-

I riphe'iy' of the piston ring; This taper is, of course, greatly exaggerated in the drawings, but is highly desirable in providing the maximum sealing effect between the cylinder and the piston carrying the piston rings and in providing minimum area of contact between the piston rings and the cylinder.

The honing stones are individually adjusted to proper radial position in any suitable manner. The means shown for this purpose comprise an adjusting screw I having an inner threaded end screwed into the threaded inner end of a bore I36 provided centrally in each stone holder II8 parallel its radial guideway II6. These radial adjusting screws I35 extend through the rim II3 of the annular base III] and each is turned by means of a knob I38 at its outer end. Each of these knobs I38 is shown as screwed on the outer threaded end of its adjusting screw I35 and held against turning relative to the adjusting screw by a lock nut I39, as best shown at the right of Fig. 8. Each adjusting screw is held against radial movement relative to the rim II3 by the hub of its knob I38 and by an enlarged flange I fast to each adjusting screw and engaging the inside of the rim II3.

It is important that each stone holder II8 be tightly held in its guideway I I 6 so that it cannot chatter and interfere with proper honing of the piston ring. To this end each holder I I8 is crowded to one side and toward the bottom of its guideway H6. To crowd each stone holder I I8 toward one side of its guideway I I 6, a pointed screw I4I is carried by the cover plate H9 above a beveled recess I42 provided at the corresponding side edge of each stone holder I I8. It will be seen, as best shown in Fig. 9, that screwing the several pointed screws MI down forces the stone holders IE8 laterally into firm engagement with the opposite side walls of the guideways H6. The stone holders are crowded against the bottoms of the guideways II 6 by set screws I43 in the cover plate H9, each bearin downwardly on its stone holder, as best shown in Fig. 9.

The piston rings to be finished are usually marked on one end face to indicate that this face is to be the top of the piston ring when inserted into the cylinder. This is usually done by stamping top in this face of the piston ring. The piston ring to be finished in accordance with the present invention may be cylindrical or may be roughly tapered to frusto-conical form, in which latter event the face marked top would be the face at the small end of the taper.

In the operation of the piston ring honing apparatus, air under pressure of, say, 30 lbs., is supplied to the lower chamber 94 of the stationary cylinder through the air pressure supply pipe 95, this air bubbling up through the usualbody of oil in the bottom of this chamber so that the compressed air carries with it a small amount of lubricant. At the start of the operation the shaft 36 and its collar or plate 58 are elevated to the position shown in Fig. 6, in which position the upper collar or plate 58 is separated from the structure thereunder so that the operator is able to place the piston ring to be finished over the hexagonal stud 8| and into the upper frustoconical part of the bore in the piston ring receiver I25. It is unnecessary that this ring be placed with precision, the ring assuming the position shown in Fig. 6 even though placed with little care. In so placing the piston ring, the operator places the ring top side down.

,At this time the upper face of the lower piston ring supporting collar or plate I8 is slightly be low the upper extremity of this lower cylindrical part I28 in the bore of the piston ring receiver I25. This initial depressed positioning of this piston ring supporting plate or collar I8 is due to the fact that at this time the chamber 90 has been vented through the port I60. Accordingly, the air pressure in this chamber has been relieved so that the tubular shaft I2 and the lower piston ring supporting collar or plate I8 has dropped to a position where the upper face of the latter is slightly below the plane of juncture of the upper frusto-conical and lower cylindrical parts I26 and I28 of the bore in the piston ring receiver I25.

The operator then introduces oil under pressure into the upper end of the hydraulic cylinder 39 through the line 44 shown in Fig. 1, relieving, of course, a corresponding amount of-oil from the line 45. This moves the piston 48 and piston rod 4i downwardly, thereby, through the bearings 48 and G9 contained within the bearin housing 56, to depress the shaft 36. This downward movement of the shaft 36 causes the upright hexagonal stud BI on the tubular shaft E2 to enter the hexagonal recess as so that these two shafts are compelled to rotate in unison.

The continued downward movement of the splined shaft 36 causes its piston ring engaging collar or disk 58 to engage the now upper face of the piston ring, this being, of course, the side opposite from that marked top. This engagement of the piston ring causes the piston ring to be moved downwardly from the frustoconical part I26 into the cylindrical part I28 of the bore in the holder I25 and into engagement with the opposing planar faces of the collars or plates 58, I8. If the end faces of the piston rin are out of parallelism, these collars or plates 58, i8 adapt themselves to this condition so that each collar or plate engages the full area of each end face of the piston ring. Thus, an important feature of the invention resides in the resilient backing for at least one of the collars or plates 53, 78 between which the piston ring is held, this resilient backing shown as comprising the ring 56 of synthetic rubber above the collar or plate 58. Because of this synthetic rubber ring 56, the collar or plate 58 is free to cock to a limited degree and hence conform itself to any reasonable out-of-parallel condition between the upper and lower faces of the piston ring. As the piston ring 2c is so moved downwardly through the diminishing lower end of the frustoconical part I26 of the bore in the holder I25, it is contracted radially inwardly. Accordingly, the piston ring 2! is held in a contracted condition in the cylindrical lower part I28 of this bore and tends to expand under its own inherent resilience. The continued downward movement of the splined shaft 36 causes the supporting collar or plate It to be depressed, this forcing downwardly the tubular shaft ?2 and causin the upper flange IS of this tubular shaft I2 to engage the upper end and depress the sleeve and thereby release the brake flange H33 of this sleeve from engagement with the stationary brake ring I64, thereby to render the tubular shaft l2 and its sleeve 85 free to rotate, this shaft and sleeve being compelled to rotate in unison through the pin 87 projecting into the longitudinal keyway provided in the tubular shaft I2. At the same time, the piston ring 26 is brought into engagement with the frustoconical faces I3! of honing stones I30.

downward movement of the sleeve 85 also brings its port 99' into register with the port 96 of its supportin stationary sleeve 9|, this port 96' communicating with the air pressure chamber- 94 of the stationary cylinder 65. Accordingly, air under pressure: is admitted to the annular chamber 90. so as to bias the tubular shaft l2 upwardly. Thisupward biasing of the tubular shaft 12 is augmented by the air pressure acting against the lower end of' the sleeve 85. The chambers 90' and 94, so containing air under the assumed pressure of 30. lbs., are therefore separate air cushioning devices which urge the lower piston ring supporting collar or plate 18 upwardly and which determine the pressure with which the piston ring 20 is held betweenthe collars or plates 58 and 18.

The operator then starts the flow of kerosene through the line 84; starts the electric motor 2|; and also alternately admits and exhausts oil to and from the lines 44 and 450i the hydraulic cylinder 39 so as to reciprocate the piston 40 therein. This reciprocation of the piston: 48 reciprocates the piston ring 20 vertically along the working faces [3| of the honing stones I39 preferably at a frequency in the order of 100 reciprocations per minute and: with a stroke suflicient to carry the leading face. of the, piston rin 2.0 slightly beyond the upper and; lower extremities of the honing. stones i'Jfl. Atv the same time the piston ring is being, rotated, preferably at a speed in the order of 115' R. P. M. by the electric motor 21, this rotation being. provided through. the belt drive 2.8;shaft 25, worm gear 30, worm wheel 3|, to the shaft 36 on which the worm wheel 3| is splined. and which is bearing downwardly upon the piston ring 20 as previously described.

In the reciprocation of the piston ring b the piston 40 within the hydraulic cylinder 39, the piston ring is biased upwardly by air pressure so that the reactance and holding pressure against the piston ring 20 is provided by an air cushion. Thus, during this reciprocation of the piston ring in contact with the honing stones, the air pressure, at the assumed value of lbs., in the chamber 94 is impressed against the under side of the sleeve 85 and is also impressed against the shoulder 15 of the tubular shaft 12 since at this time the port 96 is in communication with the annular groove as on the sleeve 85 and hence establishes an air pressure within theannular chamber 98 equal to that within the air pressure chamber 94. This position of these parts is shown in Fig, 10 and the position of theother parts of the apparatus t this time is shown in Fig. 4.

The reactance or upward biasing of thetubular shaft 12 by this air pressure is suflicient to insure retention of the contact of the piston ring 2% with the two metal collars or plates 58 and id but is of such low value that this piston ring 24) held therebetween is free to breathe or expand under its own inherent resilience into contact with the working surfaces [31 of the honing stones I33. This insures that the peripheral surface of the piston ring is honed under substantially the same conditions of confinement and resilient stress as is obtained when the ring is subsequently used in a cylinder and insures against a wavy or snaky contour which would defeat the purpose for which the piston ring is intended to be used. At the same time, to expedite the abrasive action between the piston ring and the honing stones I30, this expanding pressure of. the piston ring is augmented by fluid pressure imposed within the ring, this fluid pressure adding to the inherent expansive pressure of the confined piston ring and increasing the pressure'of the ring against the honing stones.

This fluid pressure is preferably provided by the use of kerosene or other cutting oil, which at the same time is played against the working surfaces 53! of the abrasive stones i3!) so as to keep these working surfaces in optimum cutting condition. This kerosene is supplied under pressure from the line 84 and flows upwardly through the bore 88 of the tubular shaft l2 and into the bore 82 of the hexagonal stub 8i. From this bore 82 the kerosene escapes through the radial ducts 83 into the annular chamber defined by the piston ring 2g. and the collars or plates 58 and 18 between which the piston ring is held. The pressure of the kerosene in this chamber augments the inherent expansion pressure of the piston ring 29 in contact with the honing stones i315. At the same time a part of the kerosene from this chamber escapes through the radial ducts 5B and 19 extending through the collars or plates 58 and 18, respectively. The kerosene so escaping from these radial ducts is played against the working surfaces 83! of the honing stones its so as to wash these working surfaces and keep them in a clean and sharp cutting condition. It will be observed that the kerosene is played against these working faces I3! of the honing stones with considerable force. After being so used, the kerosene flows downwardly into the chamber 93 of the stationary cylinder from which it is relieved by the kerosene drain line at H38.

It will be observed that these working faces l3! of the honing stones are not of cylindrical form but are jointly of frusto-conical tapering form so that the piston ring as is reciprocated alternately along the enlarging and contracting faces of these stones. This causes the piston ring to be honed with the beveled or frustoconical taper 32, best shown in Fig. 12. This tapering form of the piston ring is of prime, importance in providing the maximum sealing effect between the piston and the cylinder wall, a minimum area of contact being obtained between the piston ring and the. cylinder wall, and oil pump-ing, with the ring properly positioned and properly fitting the cylinder wall, being positively avoided. This frusto-conical taper of the piston ring 2e and the working faces l3l of the honing stones is illustrated in exaggerated form, this taper of the piston ring being in the order of .005 inch for the average sized piston ring.

After the. ring 2t has been sufficiently honed, thev operator admits fluid under pressure to the line 65.. of the hydraulic cylinder 33 so as to move the piston dii upwardly; cuts off the flow of kerosene under pressure from the kerosene line 8.4; and de-energizes the electric motor 2!. Raising the piston 4i! raises the, piston rod 4| and shaft. 35, thereby to raise the enlarged head 52 and collar or plate 58 engaging the new upper end face of. the honed piston. ring 2!], this being the end face opposite that marked top. The

air pressure within the lower chamber 9d of the fixed piston 55 and in the chamber 99 between the shaft l2 and sleeve and acting on the under side of the sleeve 85' and shoulder 15 of the tubular rod 2, raises this sleeve and rod, thereby causing the lower collar or plate '58 and piston ring 20 to follow the shaft 35 in its upward movement. The brake flange H13 oi: the

sleeve 85 thereupon engages the brake ring I04 so as to stop rotation of this sleeve and the tubular shaft 12, this shaft and sleeve being pinned to rotate in unison by the pin Bl. At this time the hexagonal stud 8! is in engagement with the hexagonal socket 554 so that the rotation of the shaft 35 and its motor drive is likewise subject to the braking action of the brake flange 163 against the brake ring I94, although it will be understood that a separate brake (not shown) can be provided for the shaft 36.

As the splined shaft 35 continues its upward movement the confined air pressure in the annular chamber 98 reacting against the shoulder '15 causes the tubular shaft 12 to continue to rise and follow the upward movement of the shaft 36. This movement continues until the parts reach the position shown in Fig. 5 at which time the screw 8! in the sleeve 85 reaches the bottom of its groove in the tubular shaft 12 so that further upward movement of the tubular shaft 12 is prevented and the splined shaft 36 and upper collar or plate 58 carried thereby, leave the piston ring 2B. Following this, the socket 54 in the splined shaft 36 is withdrawn from the hexagonal projection ill on the tubular shaft 12. As the sleeve 85 reaches the upper limit of its movement, the groove 98 of the shaft 72 registers with the vent port I08 of the sleeve 85, thereby venting the chamber 9E! and permitting the shaft 12 and its collar or plate 18 to settle to the position slightly below the plane of juncture of the frustoconical and cylindrical parts I26 and Us of the bore in the piston ring receiver !25. This dropping of the collar or plate 18 redeposits the piston ring 28 in the upper frustoconical part I26 of the bore in the holder I25 and from which it can be removed to be replaced with an unhoned piston ring.

The parts are now in the position assumed at the start of the description of the operation and the cycle is repeated with a fresh unhoned piston ring.

It will be understood that the operation of the apparatus can be made as automatic as may be desired so that the operator need only to press a start button to start the descending movement of the splined shaft 35, the other functions of the apparatus being automatically started and stopped in proper sequence to efiect the described cycle of operations. Also, an electro-rnagnetic brake can be applied to the splined shaft 36 in circuit with the electric motor 2! and synchronized with the engagement of the brake flange IE3 so that no strain is placed upon any of the parts. Such automatic control features are a matter of choice and design and as they are not inventive features they are not shown or described in detail.

As stone wear takes place, the honing stones 539 can be readily readjusted inwardly. For this purpose the operator loosens the set screws M4 and also loosens the pointed screws Hi, this leaving the stone holders H8 free to slide radially along the radial guideways H6. The operator then turns the knobs I38 so as to adjust the holders I I8 inwardl to the desired degree. Turning these knobs turns the screws I35 and since these screws are held against movement relative to the rim H3 of the base Hi3 and have threaded connection with the stone holders !8, the stone holders are advanced or retracted by turning the knobs When the desired adjustment of the stones I30 is achieved, the operator first tightens t e several pointed screws MI. The points of these screws bear against the faces of the inclined grooves M2 in the stone holders so as to crowd these stone holders clockwise as viewed in Fig. 8, and insure a firm fit against the corresponding sides of the grooves H6. The operator then screws down the set screws H4 which crowd the stone holders H8 against the bottoms of the grooves I I6. The stone holders are thereby locked in these grooves and cannot chatter to interfere with the proper honing operation.

From the foregoing it will be seen that the present invention provides a very rapid method and apparatus for honing expansible piston rings through the application of internal fluid pressure to agument the inherent expansion of each piston ring against the stones of the surrounding abrasive device, while at the same time each piston ring being ground is free to breathe or expand under its inherent resilience so that it is honed under substantially the same conditions of confinement as are obtained when the ring is subsequently used in a cylinder, thereby to insure a ring having true circular contour and freedom from waviness and snakiness. At the same time the rings are ground so as to be of tapered or frusto-conical form. The apparatus is quickly loaded and unloaded by the simple expedient of placing the rings in the bore in the piston ring receiver and removing the finished piston rings therefrom. As a result of these features the individual honing of the piston rings in the practice of the present invention is much faster than securing a gang of piston rings in alternate relation with driver rings and honing'the gang of rings as a group. Further, individual honin of the piston rings permits their being honed into the desired tapered form.

I claim:

1. The method of finishing a resiliently radially expansible circular article which comprises enclosing and gripping the opposite end faces of the article with a force sufficient to impart rotation thereto but insufficient to prevent radial expansion thereof, applyin fluid under pressure to the interior of said enclosed article to expand said article and urge its peripheral surface against an embracing abrasive device, and drivingly pro ducing relative movement between the article and the abrasive device through such grippin connection.

2. The method finishing a resiliently expansible circular article which comprises applying closure members to opposite end faces of said article with a force suflicient to impart rotation thereto but insufficient to prevent radial expansion thereof, applying fluid under pressure to the chamber provided by said article and closure members to expand said article and urge its peripheral surface against an embracing abrasive device, and drivingly producing relative movement between the article and the abrasive device through such grippin connection.

3. The method of finishing a resiliently radially expansible circular article which comprises permitting the article to expand within and yieldingly urge its peripheral surface against an embracing abrasive device, enclosing and gripping the opposite end faces of the article with a force sufficient to impart rotation thereto but insufficient to prevent radial expansion thereof, applying fluid under pressure to the interior of the enclosed article to augment the pressure of its peripheral surface against the abrasive device, and drivingly producing relative movement between the article and the abrasive device through such gripping connection.

4. The method of finishing a resiliently radially expansible' circular article which comprises enclosing and gripping the opposite end faces of the article with a force sufiicient to impart rotation thereto but insufficient to prevent radial expansion thereof, applying cutting oil under pres sure to the interior of said enclosed article to expand said article and urge its peripheral surface against an embracing abrasive device, drivingly producing relative movement between the article andthe abrasive device through such gripping connection, and directing a part of the cutting oil under pressure against said abrasive device to keep it in a clean and sharp condition.

5. The method of finishing a resiliently expansible circular article which comprises applying closure members to opposite end faces of said article with a force sufficient to impart rotation thereto but insufiicient to prevent radial expansion thereof, applyin cutting oil under pressure to the chamber provided by the article and closure members toexpand said article and urge its peripheral surface against the opposing working faces of an embracing abrasive device, drivingly producing relative movement between the article and the abrasive device through such gripping connection and relieving said cutting oil under pressure from said chamber against said working faces to keep the-m in a clean and sharpcondition.

6. The method of finishing a resiliently radially expansible circular article which comprises arrangin the working faces of an abrasive device in circular opposing relation and at an angle to the axis of the device, permitting the article to expand within and yieldingly urge its peripheral surface against said workin faces of the abrasive device, gripping the end faces of the article with a force sufficient to impart rotation thereto but insufficient to prevent radial expansion thereof, and drivingly producing relative movement between the article and the abrasive device through such gripping connection to produce a frusto-conical bevel on the periphery of said article.

7. The method of finishing a resiliently radially expansible circular article which comprises arranging the working faces of an abrasive device in opposing circular relation and at an angle to the axis of the device, enclosing and gripping the opposite end faces of the article with a force ufficient to impart rotation thereto but insufficient to prevent radial expansion thereof, applying fluid under pressure to the interior of said enclosed article to expand said article and urge its peripheral surface against said workin faces of the abrasive device. and drivingly producing relative movement between the article and the abrasive device through such gripping connection to produce a frusto-conical bevel on the periphery of said article.

8. The method of'finishing a resiliently radially expansible circular article which comprises arranging the working faces of an abrasive device in opposing circular'relation and at an angle to the axis of the device, enclosing and gripping the opposite end faces of the article with a force sufiicient to impart rotation thereto but insufficient to prevent radial expansion thereof, applying cutting oil under pressure to the interior of said enclosed article to expand said article and urge its peripheral surface against said working facesof the abrasive device, drivinglyproducing relative movement between the article and the abrasive device through such gripping connection to produce a frusto-conical bevel on the periphery of said article, and directing said cutting oil under pressure against said working faces to keep them in a clean and sharp condition.

9. The method of finishing a resiliently expansible piston ring having non-parallel, planar end faces, which comprises yieldingly applying the flat faces of closure members to the opposite nonparallel end faces of said piston rin with a force sufficient to impart rotation thereto but insufiicient' to prevent radial expansion thereof, introducing fluid under pressure into the chamber provided by said piston ring and closure members to expand said piston ring and urge its peripheral surface against an embracing abrasive device, and drivingly producin relative movement between the piston ring and the abrasive device through such gripping connection.

10. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive deice having its working faces in opposed circular relation, a plate adapted to engage each end face of said circular ring and hold said rin concentrically within said working faces, means for holding said plates against said end faces of said ring with a force sufficient to impart rotative movement to the ring, but insufficient to prevent radial expansion thereof into engagement with said working faces, means for moving said plates relative to said abrasive device to produce relative movement between said ring and working faces, one of said. plates being provided with an opening therethrough leading to the chamber provided by said plates and ring, a fluid pressure supply line operatively connected with said opening and supplying fluid under pressure to said. chamber to expand said ring and provide the desired contact pressure between said ring and working faces.

ll. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its' working faces in opposed circular relation, a pair of shafts concentric with said working faces and arranged in opposed relation to each other, a plate non-rotatably secured to each of said shafts at the end opposing the other shaft and adapted to engage the corresponding end face of said circular ring and hold said ring concentrically within said working faces, means biasing said shafts toward each other with a force. sufficient to impart rotative movement from one of said. shafts and its plate to the ring but insufficient to prevent radial expansion thereof into engagement with said. workin faces, means for rotating said one of said shafts relative to said abrasive device, and a fluid pressure supply line communicating with the chamber provided by said plates and. ring and supplying fiuid under pressure to expand said ring and provide the desired contact pressure between said ring and Working faces.

12. Apparatus for finishing r siliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a pair of shafts concentric with said working faces and arranged in opposed relation to each other, a plate non-rotatably secured to each of said shafts at the end opposing the other a force sufficient to impart rotative movement from said shafts and plates to the ring but insufficient to prevent radial expansion thereof, means for rotating said shaft and plate assembly relative to said abrasive device, one of said shafts being provided with a bore communicating with the chamber provided by said plates and ring, and a fluid pressure line communicating with said bore and supplying fluid under pressure to said chamber to expand said ring and provide the desired contact pressure between said ring and working faces.

13. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a pair of shafts concentric with said working faces and arranged in opposed relation to each other, a plate non-rotatably secured to each of said shafts at the end opposing the other shaft and adapted to engage the corresponding end face of said circular ring and hold said ring concentrically within said Working faces, an out-ofround stud projecting from the end of one of said shafts and adapted to fit an out-of-round socket in the opposing end of the other of said shafts, means for moving said shafts axially toward each other with a force sufficient to impart rotative movement from said shafts and plates to the ring but insufficient to prevent radial expansion thereof, means for rotating said shafts and plate assembly relative to said abrasive device, said one of said shafts and its stud being provided with bores communicating with the chamber provided by said plates and ring, and a fluid pressure line communicating with said bores and sup-plying fluid under pressure to said chamber to expand said ring and provide the desired contact pressure between said ring and working faces.

14. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a plate adapted to engage each end face of said circular ring and hold said ring concentrically Within said working faces, means for holding said plates against said end faces of said ring with a force sufficient to impart rotative movement to the ring but insufncient to prevent radial expansion thereof, means for moving at least one of said plates relative to said abrasive device to produce relative movement between said ring and working faces, one of said plates being provided with an opening therethrough leading to the chamber provided by said plates and ring, a cutting oil pressure supply line operatively connected with said opening and supplying cutting oil under pressure to said chamber to expand said ring and provide the desired contact pressure between said ring and working faces, and means discharging said cutting oil under pressure against said working faces to keep said working faces in a clean and sharp condition.

15. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a plate adapted to engage each end face of said circular ring and hold said ring concentrically Within said working faces, means for holding said plates against said end faces of said ring with a force sufficient to impart rotative movement to the ring but insufficient to prevent radial expansion thereof, means for moving at least one of said plates relative to said abrasive device to produce relative movement between said ring and working faces, one of said plates being provided with an opening therethrough leading to the chamber provided by said plates and ring, a cutting oil pressure supply line operatively connected with said opening and supplying cutting oil under pressure to said chamber to expand said ring and provide the desired contact pressure between said ring and working faces, and means discharging said cutting oil under pressure against the said working faces to keep said working faces in a clean and sharp condition, comprising a duct extending through at least one of said plates from said chamber toward said cutting faces.

16. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a pair of shafts concentric with said working faces and arranged in opposed relation to each other, a plate non-rotatably secured to each of said shafts at the end opposing the other shaft and adapted to engage the corresponding end face of said circular ring and hold said ring concentrically within said Working faces, means biasing said shafts toward eachother With a force sufiicient to impart rotative movement from said shafts and plates to the ring but insufficient to prevent radial expansion thereof, means for rotating said shaft and plate assembly relative to said abrasive device, one of said shafts being provided with a bore communicating with the chamber provided by said plates and. ring, a cutting oil pressure line communicating with said bore and supplying cutting oil under pressure to said chamber to expand said ring and provide the desired contact pressure between said ring and working faces, and means discharging said cutting oil under pressufe against said working faces to keep said Working faces in a clean and sharp condition.

17. Apparatus for finishing resiliently expansible circular rings the end faces of which may be non-parallel, comprising an abrasive device having its working faces in'opposed circular re-- lation, a plate adapted to engage each face of said circular ring and hold said ring concentrically within said working faces, a support for each of said plates, a resilient member interposed between one of said supports and the corresponding plate and permitting said corresponding plate to cook and adapt itself to the non-parallel end face of said ring contacted thereby, means for biasing said plates toward each other with a force suflicient to impart rotative movement to the ring but insuflicient to prevent radial expansion thereof, and means for moving the assembly of plate, ring and supports relative to said abrasive device to produce relative movement be-' tween said ring and working faces.

18. Apparatus for finishing resiliently expansible circular rings the end faces of which may be non-parallel, comprising an abrasive device having its Working faces in opposed circular relation, a pair of shafts concentric with said working faces and arranged in opposed relation to each other, a rubber member non-rotatably secured to the end of one of said shafts opposing the other shaft, a plate secured against said rubber member to permit said plate to cook relative to said shaft, a plate non-rotatably secured to the opposing end of the other of said shafts, said plates being adapted on axial movement of said shafts toward each other to engage the opposite end faces of said circular ring, means biasing said shafts toward each other with a force sufficient to impart rotative movement from one of said shafts and its plate to the ring but insufii- 17 cient to prevent radial expansion thereof, and means for rotating said one of said shafts rela-- tive; tosaid. abrasive device.

19.. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive devicehaving it working faces in opposed frusto-conical relation, means for holding said ring in said abrasive device with a: force sufiicient. to impart rotative movement. to the ring; but insufficient to:

prevent radial expansion thereof into engagement with said working faces, and. means for moving, said holding means relative. to said abrasive device to provide a frusto-conical taper on the-periphery of said ring.

20-. Apparatusfor finishing resiliently expansible circular rings, comprising an. abrasive device. having its working faces in opposed frusto-conical relation, a plate adapted to engage each end face of said circular ringand hold said ring within said working faces, means for holding said plates against said end faces of said ring, with a force sufiicient to impart rotative movement to the ring but insuiiicient to prevent radial expansion thereof into engagement with said working faces, means for moving said plates relative to said. abrasive device to produce relative movement between saidringand workin faces and provide a frusto-conical taper on the periphery of said ring, one of said plates being provided with an opening therethrough leading to the chamber provided by said, plates and ring, a fluid pressure supply line operativeiy connected with said opening and supplying fduid under pressure to said chamber to expand said ring and provide the desired contact pressure between said ring and Working faces and means for rotating said shaft and plate assembly,

2-1.. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a plate adapted: to engage each end face of said circular ring and holdsaid ring concentrically within said workingfaces, a device for reciprocati-ng one of said plates lengthwise of the axis of said working faces, a. cushion of compressed air biasingthe. other of said plates towardsaid one of said plates and holding said plates against said end facesv of said ring with a force sufficient toimpart rotative movement to the ring but insufiicient to prevent radial expansion. thereof into engagement with said working faces, and means for rotating said assembly of plates: and ring.

22. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed: circular relation, a pair of shafts concentric with said Working faces and arranged in opposed relation with each other, a plate non-rotatably secured to each of. said shafts at the end opposing the other shaft and adapted to engage the corresponding end face of said circular ring, and hold said ring concentrically within said working faces, a device for reciprocatin one of said shafts, a compressed air cushioning device biasing the other of said shafts axially toward said: one of said shafts and holding said plates against said end faces of said ring with a force sufiicient to impart. rotative movement to said ring but insufiicient to prevent radial expansion thereof into engagement with said working faces, and means for rotating one of said shafts.

23.. Apparatusv for finishing. resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a pair of shafts concentric with said working faces and arranged in opposed relation with each other, a platenon-rotatably secured to each ofsaid shafts at the end opposing the other shaft and, adapted to engage the corresponding end. face of saidcircular ring and hold said ring concentrically Within said working iaces, a device for. reciprocatingone of said shafts and moving, said one of said shafts.- axiall-y to an extreme positionaway from theother of said shafts to release said ringfrom between said plates, a compressed air cushioning device biasing the other of saidshafts. axially toward said: oneof said shafts and holding said plates against said end faces of said ring witha force sufficient to impart rotative movement to said ring but insufiicient to prevent radial expansion thereof into engagement with said. working faces, valve means connecting said air cushioning; device, with a source of air under pressure when said reciprocating device is reciprocating said one of said shafts, valve means exhausting said air cushioning device when saidre ciprocating device moves said one of said shafts to. said extreme position, and means for rotating one of said shafts.

24. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its Working faces in opposed circular relation, a pair of shafts concentric with said WOlk-- ing faces and arranged in opposed relation with eachother, a plate non-rotatably secured to each of said shafts at the end opposing the other shaftand adapted to engage the corresponding end. face of said circular rin and hold saidring concentrical-ly within said working faces, a device for reciprocating one of said shafts and moving said one of said shaftsv axially to an extremeposition away from the other of said shaftstorelease said rin from between. said plates, the other of said shafts being provided with a cylindrical endofv reduced diameter remote from the abrasive de-- vice, a sleeve fitting aroundsaid other of said shafts and having its bore. at. one end of larger diameter to fit the enlarged diameter of the corresponding end of the other of said hafts and its bore at theother end of smaller diameter to fit the reduced diameter of said other of said shafts and forming an annular air cushion chamber between said other of said shafts and said sleeve, said. sleeve being provided: with a port extending through. the wall of said sleeve and registering with said chamber when saidreciprocati-ng device isreciprocating said one of said shafts, an air pressure line operatively connected with said port to supply compressed air to said chamber and hold said plates against said end faces of said ring with a force sufficient to impart rotative movement to said ring but insufficient to prevent radial expansion thereof into engagement with said working faces, said sleeve being. provided with an exhaust port extending through the wall of said sleeve and registering with said chamber when said reciprocating devicemoves said one of said shafts to saidextreme position, and means for rotating one of said shafts.

25. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relatic-1r, a pair of shafts concentric with said working faces and arranged in opposed; relation with eachother,. a sleeve around one of said shafts and r0- tating therewith but axiallymovable thereon, cooperating plates carried at the opposing ends of the other; of said shafts and said sleeve and adapted to engage the opposite end faces of said ring and hold said ring concentrically within said working faces, a device for reciprocating said other of said shafts, a compressed air cushioning device between said one of said shafts and said sleeve and biasing said one of said shafts axially toward said other of said shafts, a separate compressed air cushioning device biasing said sleeve toward said other of said shafts, said air cushioning devices holding said plates against said end faces of said ring with sufficient force to impart rotative movement to said ring but insufiicient to prevent radial expansion thereof into engagement with said working faces, and means for rotating said shaft, sleeve and plate assembly.

26. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a pair of shafts concentric with said working faces and arranged in opposed relation with each other, a sleeve around one of said shafts and rotating therewith but axially movable thereon, cooperating plates carried at the opposing ends of the other of said shafts and said sleeve and adapted to engage the opposite end faces of said ring and hold said ring concentrically within said working faces, a device for reciprocating said other of said shafts, a compressed air cushioning device between said one of said shafts and said sleeve and biasing said one of said shafts axially toward said other of said shafts, a separate compressed air cushioning device biasing said sleeve toward said other of said shafts, said air cushioning devices holding said plates against said end faces of said ring with sufficient force to impart rotative movement to said ring but insufficient to prevent reduced expansion thereof into engagement with said working faces, means for supplying compressed air to said first air cushioning device from said second air cushioning device during the reciprocating movement of said ring in contact with said working faces, andmeans for venting said first air cushioning device when said ring is retracted axially by said shaft, sleeve and plate assembly from contact with said working faces, and means for rotating said shaft, sleeve and plate assembly 27. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed circular relation, a pair of shafts concentric with said Working faces and arranged in opposed relation with each other, a sleeve around one of said shafts and rotating therewith but axially movable thereon, cooperating plates carried at the opposing ends of the other of said shafts and said sleeve and adapted to engage the opposite end faces of said ring and hold said ring concentrically within said working faces, a device for reciprocating said other of said shafts, a compressed air cushioning device between said one of said shafts and said sleeve and biasing said one of said shafts axially toward said other of said shafts, a separate compressed air cushioning device biasing said sleeve toward said other of said shafts, said air cushioning devices holding said plates against said end faces of said ring with sufficient force to impart rotative movement to said ring but insufficient to prevent radial expansion thereof into engagement with said working faces, a brake flange on said sleeve, a brake ring engaging with said brake flange when said ring is retracted axially by said shaft, sleeve and plate assembly from contact with said working faces, and means for rotating said shaft, sleeve and plate assembly.

28. Apparatus for finishing resiliently expansible circular rings, comprising an abrasive device having its working faces in opposed relation about a vertical axis, a pair of vertical shafts coaxial with said axis and arranged in opposed relation with each other, a plate non-rotatably secured to each of said shafts at the end opposing the other shaft and adapted to engage the corresponding end face of said circular ring and hold said ring concentrically within said working faces, means axially reciprocating one of said shafts and adapted to separate said one of said shafts and its plate from contact with said ring, a cushioning device biasing the other of said shafts toward said one of said shafts during the reciprocation thereof with a force sufficient to impart rotative movement from either of said plates to said ring but insufficient to prevent radial expansion thereof, a stationary ring receiver arranged above said abrasive device and having a downwardly contracting frusto-conical bore concentric with and above said working faces and into which the rings to be honed are placed upon said plate of said other of said shafts to be engaged by said plate of said one of said shafts and acting to compress said ring when said plates move said ring into cooperative relation with said working faces, and means for rotating said shaft and plate assembly.

29. Apparatus for finishing resiliently expansilole circular rings, comprising an abrasive device having its working faces in opposed relation about a vertical axis, a pair of vertical shafts coaxial with said axis and arranged in opposed relation with each other, a plate non-rotatably secured to each of said shafts at the end opposing the other shaft and adapted to engage the corresponding end face of said circular ring and hold said ring concentrically within said working faces, means axially reciprocating one of said shafts and adapted to separate said one of said shafts and its plate from contact with said ring, a compressed air cushioning device biasing the other of said shafts toward said one of said shafts during the reciprocation thereof with a force sufiicient to impart rotative movement from either of said plates to said ring but insufficient to prevent radial expansion thereof, a stationary ring receiver arranged above said abrasive device and having a downwardly contracting frusto-conical bore concentric with and above said working faces and in to which the rings to be honed are placed upon said plate of said other of said shafts to be engaged by said plate of said one of said shafts and acting to compress said ring when said plates move said ring into cooperative relation with said working faces, and means for rotating said shaft and plate assembly.

MARSDEN C. I-IUTTO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,195,056 Wallace Mar. 26, 1940 2,318,837 Connor May 11, 1943 2,422,418 l-Iutto June 17, 1947 

